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Rambling robots show human efficiency

The walking robots made by (from left to right) Delta, MIT and Cornell stride like humans

(Image: Steven Collins)

A trio of androids that amble along with exceptional power efficiency and “instinctive” co-ordination were unveiled for the first time on Thursday.

The three mechanical bipeds, built by researchers from Cornell University, the University of Michigan and Massachusetts Institute of Technology in the US and Delft University in the Netherlands, respectively, walked along in an amiable, if somewhat awkward fashion.

The surprisingly natural walkers were revealed at the annual meeting of the American Association for the Advancement of Science (AAAS) in Washington DC, US.

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The most advanced commercial robots, including Honda’s humanoid bot, Asimo, typically require a multitude of motors and sensors in each joint – as well as powerful adaptive software – to remain steady while walking.

But the new bots instead use simple mechanical dynamics and minimal motorisation to stride along. The shape of each robot’s frame and joints naturally enable them to walk along without requiring much exertion. A similar fundamental simplicity underlies the way in which humans walk.

Body dynamics

“Our robots demonstrate that utilising the natural dynamics of the body can make robots much more efficient,” says Steve Collins, a member of the team from the University of Michigan. “For any autonomous robots to be practical, they must be energetically efficient.”

As well as contributing to the development of more power-efficient and versatile humanoid machines, the researchers say the robots could lead to better, more effective artificial limbs.

“The walking looks more natural, because it is,” says Richard Walker, who works at the Shadow Robot Company in the UK. “To get human-like walking, and then to go from there to more complex bipedal movements, this is the right approach.”

The researchers took their inspiration from mechanical walking toys that automatically stroll down a slope in response to gravity. By attaching a few motors to such mechanisms they were able to make robots that will happily amble along a flat surface.

Learning algorithms

Two of the three robots, those developed at Cornell and Delft, are relatively simple, yet exhibit remarkable power efficiency. Whereas Asimo consumes about 10 times as much power as a walking human, these robots use about the same amount of energy as the average person.

The third robot – built at MIT and dubbed “Toddler” – is more advanced, employing a learning algorithm to adapt to its terrain. “Learning has not been used often in the context of bipedal walkers,” says Max Lungarella, a robotics researcher at the University of Tokyo in Japan. “So conceptually, Toddler is the most innovative.”

Hiroshi Yokoi, also at the University of Tokyo, adds that the research should help with the development of more intelligent and more realistic artificial legs and feet.

“It is clear this type of robot will be a test bed for the scientific model of natural walking. It has a great potential for prosthetic applications, to support the natural walking of patients,” he told New Scientist.

But the researchers will have to devise a way to combine simple dynamics with increased control for the technique to be used in practical robots, says Art Kuo, in independent researcher at the University of Michigan.

“The robots here may be 10 times more efficient, but none of them can climb stairs. New technology will need to be developed to handle that,” he says.